Original Battery for: Casio W-800 Watch. Compatiable with models: A178WEA, DBC-32, AE-1000, AE-1100, AE-1200, AE-2000, AMW-700, AMW-710, AQ-180, AW-80, AW-81A, W-82, CHR-100, DB-36, DB-360, F-200, F-201, HDC-600, MRP-700, GW-100, STR-300, W-213, W-734, W-752, W-753, W-755, W-756, W. Casio Men's W-800H-1AV Watch Digital Multi Function Sports 10 Year Battery New.

Casio 800h Watch Battery Replacement

• LED light
  A light-emitting diode (LED) is used to illuminate the watch face.
• Second time zone
  A second location time can be set and called up. Ideal if you frequently make overseas calls.
• Stopwatch function - 1/100 sec. - 24 hours
  Elapsed time, split time and final time are measured with 1/100-sec accuracy. The watch can measure times of up to 24 hours.
• Multi alarm
  This model is equipped with a multifunctional alarm. This clock has the perfect alarm for any type of appointment. The model is equipped with a total of four repeat alarms: 1. Daily alarm, sounds at the same time each day, 2. Date alarm, e.g. to help you remember birthdays, 3. Monthly alarm, sounds on the same day at the same time each month, 4. Alarm for every day of a particular month.
• Snooze feature
  Each time you stop the alarm, it sounds again after a few minutes.
• Automatic calendar with Date, Day and Month
  Once set, the automatic calendar always displays the correct date.
• 12/24-hour timekeeping
  Times can be displayed in either a 12-hour or 24-hour format.
• Acrylic Glass
  The acrylic is easy and relatively unbreakable.
• Resin case
  The resin housing is the ideal everyday companion. It is durable, lightweight and relatively insensitive to cold, heat or other external influences.
• Resin band
  Synthetic resin is the ideal material for wrist straps thanks to its extremely durable and flexible properties.
• Buckle
  The bracelet is equipped with a buckle.
• Long Battery Life
  10 years, 1 battery. Newly developed electronics ensure significantly lower energy consumption.
• Water resistance classification (10 bar)
  Perfect for swimming and snorkelling: the watch is water resistant to 10 bar according to ISO 22810.
• Dimensions (H x W x D)
  44,2mm x 36,8mm x 13,4mm
• Weight
  approx. 37 g

Availability of models and/or lineups may differ depending on the country or region.
Technical amendments and errors excepted. The sizes in figures do not correspond to the original sizes.
The colours may differ slightly from the original.

Usually, I wear an old Accutron 214 wristwatch, but the possibility of an upcoming long sailing trip had me thinking that I should get something a little more durable and easier to replace, ideally with an alarm.

Other than the alarm being a bit underwhelming, I’m happy with my new Casio W-800H, especially following this quick modification to enable a countdown timer!I had seen a reference to adding the timer on the Internet, including a mention of 4 more programmable alarms, but all the documentation on it seemed to be in the form of youtube videos or forum threads mostly full of pictures of dude’s wrists.After some time looking through those, not finding the meaning of jumpers that I’ve numbered 1-5 below, I set out to improve the Internet -just a little- by making some documentation that’s a little more pragmatic:

Casio makes a bajillion watches, of many different models.Within those many models are a few series where each model in a series has similar features to the other models in the same series.By making a small number of different PCBs for the series, and configuring them per watch model, Casio saves lots of engineering effort and manufacturing cost.In this case, the configuration is done via solder jumpers; we’re going to tell the PCB that it’s in a slightly fancier watch!

You’ll need:

• A watch - this is based on a W-800H, but there are bound to be other models with the same PCB.
• #00 philips (it may actually be JIS?) screwdriver
• Fine tweezers or X-Acto type tool, for prying
• Fine soldering iron
• Fine solder and/or wick

Casio 800h Watch Battery

Steps

1. Take the watch apart, remove the battery as if replacing it.
2. The “movement” (I presume that’s what it’s called in an electronic watch…) is a plastic clamshell, with the PCB and battery holder attached to one side, and the LCD attached to the other. The clamshell is held together with a bit of stamped steel - gently lift the steel clips and pry apart the clamshell. The PCB should stay with the battery side of the clamshell, be careful not to pull it away from that side, because there are some tiny springs retained there.
3. A white plastic spacer may fall out from between the LCD and PCB, and perhaps one or both elastomeric connectors (rectangular rubber looking thingies that electrically connect the PCB with the LCD). When reassembling, I think the spacer thing is oriented as in the below photo, and the elastomeric connectors drop in to the slots behind the top and bottom edges of the LCD.
4. Set solder jumpers as desired - “open” means solder removed, “shorted” or “closed” means connected with a blob of solder.
5. Reverse above instructions; you may need to clear the watch memory as the sticker on the battery instructs - I didn’t bother and things seemed to work OK, in the 14 times I reassembled my watch to figure out the below table.

Unfortunately, I didn’t consider that some of the jumpers might affect something about the piezo beeper until starting to write this post…

Here’s the top of the PCB, showing the solder jumpers:

Here’s what I think the orientation of the spacer should be; the two sides of the clamshell are opened like a book: